Their battles have put on display a striking culture clash: the Silicon Valley startup mentality, in which disruptive technologies quickly win consumers, versus Washington’s inside game, mastered by long-established companies with deep government connections and knowledge.

And if there’s a No. 1 understood rule for those seeking to sell to the government, it’s this: Don’t sue your customer.

SpaceX, founded by billionaire entrepreneur Elon Musk, broke that rule in April, when the company sued the Air Force to reopen a lucrative satellite launch contract awarded to United Launch Alliance, a joint venture of two of the biggest defense giants: Lockheed Martin and Boeing.

Palantir hasn’t filed a lawsuit, but its top advocate in Congress has forcefully accused the Army of making it difficult for soldiers in Afghanistan to get their hands on its intelligence software.

The companies’ public battles have raised questions in the industry and on Capitol Hill about the Pentagon’s procurement system, which is regularly criticized but rarely changed, and have highlighted the significant role Congress can play in settling these kinds of disputes.

“They were very aggressive,” said one defense lobbyist, discussing the issue on condition of anonymity. “They didn’t navigate the process correctly in the beginning and made a lot of enemies.”

SpaceX and its Washington backers say they had to be aggressive to shake up the Pentagon’s massive and staid acquisition system.

Indeed, former Pentagon procurement officials say there’s a high barrier blocking new entrants from government work, including lengthy regulations and stringent accounting standards.

Brett Lambert, the former director of DOD industrial policy, said commercial companies have tried to sell to the Pentagon only to give up after running into the byzantine Pentagon procurement system.

“The problem you have is an institutional problem,” he said. “Those of us who wanted to open up and take advantage of commercial capabilities, sometimes you may find you’re leading and looking behind you and seeing that nobody’s there.”

Jacques Gansler, a former Pentagon acquisition chief, said the system is simply averse to change. “Large institutions naturally have more resistance,” said Gansler, now a professor at the University of Maryland and a ULA consultant.

Pentagon officials have long said they want to encourage competition, including companies they might not regularly work with.

“I like competition, and I think there is now a global marketplace out there,” Frank Kendall, the Pentagon’s chief weapons buyer, said in a speech last year. “We don’t have a monopoly on good ideas, and we’re open to competitors.”

The challenges the two companies have faced have not gone unnoticed on the Hill.

Companies like SpaceX and Palantir “have an inherent disadvantage because they are not traditional military suppliers,” said Rep. Mac Thornberry (R-Texas), a senior member of the House Armed Services Committee and the leader of an acquisition reform effort. “How can we take advantage, not only of the competition, but the technology they have? And that’s what we grapple with.”

And after running into roadblocks with the military, both companies have turned to congressional allies to force the issue.

Sen. John McCain (R-Ariz.) has slammed ULA for cost overruns and for operating as a monopoly, while Rep. Duncan Hunter (R-Calif.), who backs Palantir, has launched a crusade against the Army’s competing program, blasting the service for problems with its system.

Still, well-established defense contractors have their own Hill backers and have enlisted their help in staving off new competitors. Rep. Mike Rogers (R-Ala.), a Lockheed supporter, included language in his Strategic Forces subcommittee markup that said “the Air Force should continue the current block buy contract” for its launch program. But that language was quietly stripped from the full committee version — a win for SpaceX.

Even as backers of Palantir and SpaceX rail against the existing system, the companies are learning to play the inside game. Both have ramped up their lobbying spending. In the past year, SpaceX has nearly doubled its lobbying dollars, spending $174,000 in the first quarter of 2014 and hiring three new outside lobbying firms.

Palantir’s push came in 2013, when the company boosted its lobbying spending to more than $1.1 million, an increase of nearly 90 percent from the prior year.

Even so, the numbers pale in comparison to the lobbying of companies like Lockheed Martin and Boeing, which each spent more than $14 million in 2013.

Loren Thompson, a defense industry consultant whose clients include Lockheed, said he doesn’t think SpaceX has an inherent disadvantage taking on ULA, because “whatever it lacks in terms of Washington connections it makes up for in agility.”

“I’m not convinced that SpaceX will ever be a major player in launching military satellites,” Thompson said. “However, I think the difficulty that an entrepreneur like Musk faces breaking into this system does raise questions about the federal acquisition culture.”

Perhaps the greatest challenge that comes with taking on the military is potentially losing a lucrative customer. SpaceX has filed suit against the Air Force, but it still has every intention of making the service a customer.

The company, established in 2002 by PayPal co-founder Musk, is working with the Air Force to get its rockets certified for military launches.

At an event last week, Gwynne Shotwell, SpaceX’s chief operating officer, said newer companies face an inherent disadvantage. SpaceX, which declined to be interviewed for this article, has argued that the Air Force is overpaying for ULA’s services and could save money with SpaceX technology.

“The Air Force is comfortable with ULA,” she said. “Of course we’re at a disadvantage: They have more money to spend on lobbyists; they have more money to spend on marketing.”

But Michael Gass, who heads ULA, disagreed.

“In most circles, people would say there’s a curse of the incumbent,” Gass said in an interview. “A new entrant can promise things. … They can advertise prices without a whole lot of transparency.”

For its part, Palantir, founded in 2004 — also by PayPal alums — has based its case on the superiority of its product.

The company’s advocates argue its software has gotten good reviews from some intelligence analysts in Afghanistan who used it to sift through data on enemies suspected of planting roadside bombs.

Hunter, Palantir’s congressional backer, has contended that the Army has made it difficult for soldiers to get Palantir’s software — even when their commanders requested it — and has highlighted failures with the service’s multibillion-dollar program of record, the Distributed Common Ground System, built by big-name defense companies.

Palantir has had some successes. Congress slashed funding for DCGS in its 2014 appropriations measure, and Army acquisition chief Heidi Shyu made a trip to Palo Alto to meet with company executives.

“While in general we do not comment on these issues, it is accurate that our commercial growth is outstripping our growth in government,” Palantir said in a statement. “Reform of the acquisition process in the federal space is something that would benefit not just Palantir but our society as a whole.”